Illustration what the Typhoon imager can do for you: Four color competitive gel shift assay to determine the relative affinities of the Salmonella spp. bacteriophage P22 repressor Mnt. In the assay the repressor is allowed to bind four different oligonucloetides labeled with FAM, HEX, TAMRA and ROX respectively at the same time. The intensities for each fluorophore in a lane are related directly to the relative affinity of the repressor protein for the oligonucleotide used. (from GE Healthcare)